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United States Patent |
5,608,159
|
Carcone
,   et al.
|
March 4, 1997
|
Freeze seal and freeze clamp for cables, wires, optical fibers and the
like
Abstract
A freeze device for an elongated element includes a pressure vessel
disposed about at least a part of the element and a freeze seal between
the part of the elongated element and the pressure vessel. The freeze seal
includes a frozen material exerting a force inwardly against the part of
the element and outwardly against the pressure vessel by virtue of having
been frozen in situ such that the frozen material thereby seals the
elongated element to the pressure vessel.
Inventors:
|
Carcone; John M. (Westwood, NJ);
Engelberth; Jon W. (Denville, NJ);
LaGrotta; James T. (Boonton Township, Morris County, NJ);
Newell; Joseph V. (East Hanover, NJ)
|
Assignee:
|
Lucent Technologies Inc. (Murray Hill, NJ)
|
Appl. No.:
|
417423 |
Filed:
|
April 5, 1995 |
Current U.S. Class: |
73/49.8; 62/66; 62/293; 226/8 |
Intern'l Class: |
G01M 019/00; F16L 003/08; F16L 007/02 |
Field of Search: |
138/89,90,91
226/8,93
405/154
62/66,293,37,40
73/40.5 R,49.8,49.1,49.5
|
References Cited
U.S. Patent Documents
3041850 | Jul., 1962 | Nunn | 62/293.
|
3623337 | Nov., 1971 | Tremont | 62/66.
|
3827282 | Aug., 1974 | Brister | 73/40.
|
3926006 | Dec., 1975 | Brooks et al. | 405/154.
|
4112706 | Sep., 1978 | Brister | 62/514.
|
4220012 | Sep., 1980 | Brister | 62/130.
|
4267699 | May., 1981 | Bahrenburg | 62/66.
|
4314577 | Feb., 1982 | Brister | 137/13.
|
4370862 | Feb., 1983 | Brister | 62/66.
|
4416118 | Nov., 1983 | Brister | 62/66.
|
4428204 | Jan., 1984 | Brister | 62/62.
|
4433556 | Feb., 1984 | Brady | 62/293.
|
4441328 | Apr., 1984 | Brister | 62/53.
|
5125427 | Jun., 1992 | Cantu et al. | 137/13.
|
Primary Examiner: Brock; Michael
Claims
What we claim is:
1. A freeze device for an elongated element comprising a pressure vessel
having an interior and a passage means leading to said interior, said
elongated element having one part extending through said passage means and
another part disposed in said interior of said pressure vessel, freeze
means between said one part of said elongated element and said passage
means, said freeze means including a frozen material exerting a force
inwardly against said one part of said elongated element and outwardly
against said passage means by virtue of having been frozen in situ such
that said frozen material thereby seals said elongated element in said
passage means of said pressure vessel.
2. A freeze device according to claim 1 wherein said elongated element is
selected from the group consisting of cables, wires and fibers.
3. A freeze device according to claim 1 wherein there are a plurality of
said elongated elements such that said freeze means simultaneously seals
said plurality of elongated elements in said pressure vessel.
4. A freeze device according to claim 3 wherein at least some of said
plurality of elongated elements have different diameters.
5. A freeze device according to claim 1 wherein said pressure vessel is an
elongated pipe.
6. A freeze device according to claim 1 wherein said frozen material
comprises ice.
7. A freeze device according to claim 1 further comprising pressurizing
means for introducing a fluid under pressure into said interior of said
pressure vessel for subjecting said other part of said elongated element
to pressure testing within said interior of said pressure vessel.
8. A freeze device according to claim 1 wherein said elongated element is a
conductor, and further comprising a hardware component connected to said
conductor, said component being disposed in said pressure vessel.
9. A freeze device according to claim 1 wherein said passage means and said
pressure vessel include cooperable mounting means for mounting said
passage means on said pressure vessel.
10. A freeze device according to claim 1 wherein said freeze means
comprises a first elongated pipe disposed within a second elongated pipe,
said elongated element passing through said first elongated pipe, said
frozen material being disposed between said two pipes, between said first
pipe and said elongated element, and between said second pipe and said
passage means.
11. A freeze device according to claim 10 wherein said frozen material has
a longitudinal length terminating at an inner end face within said
pressure vessel and an outer end face terminating outside of said pressure
vessel, said first and second pipes each having a longitudinal length
greater than said longitudinal length of said frozen material.
12. A freeze device according to claim 11 wherein said first and second
pipes each have an inner end portion which extends into said pressure
vessel further than said inner end face of said frozen material, said
first and second pipes each having an outer end portion which extends
outside of said pressure vessel beyond said outer end face of said frozen
material.
13. A freeze device for an elongated element comprising a pressure vessel
having a first through passage spaced from a second through passage, an
elongated element having a first part disposed in said first through
passage and a second part disposed in said second through passage, first
freeze means between said first part of said elongated element and said
first through passage, said first freeze means including a first frozen
material exerting a force inwardly against said first part of said
elongated element and outwardly against said first through passage by
virtue of having been frozen in situ such that said first frozen material
thereby seals said first part of said elongated element in said first
through passage, second freeze means between said second part of said
elongated element and said second through passage, said second freeze
means including a second frozen material exerting a force inwardly against
said second part of said elongated element and outwardly against said
second through passage by virtue of having been frozen in situ such that
said second frozen material thereby seals said second part of said
elongated element in said second through passage.
14. A freeze device according to claim 13 wherein said first and second
freeze means each have longitudinal axes, said pressure vessel being an
elongated pressure vessel having a longitudinal axis which is generally
coincident with said axes of the first and second freeze means.
15. A freeze device according to claim 13 wherein said first and second
freeze means each have longitudinal axes which are spaced from one another
and which are generally parallel to one another.
16. A freeze device according to claim 13, further comprising pressurizing
means for introducing a pressurized fluid into said pressure vessel.
17. A freeze device according to claim 13 wherein said elongated element is
used with a device to be pressure tested, said device being disposed in
said pressure vessel, said elongated element having a first portion which
is connected to said device and which extends from said device to said
first part of said elongated element, said elongated element having a
second portion which is connected to said device and which extends from
said device to said second part of said elongated element, and
pressurizing means introducing pressurizing fluid into said pressure
vessel to effect pressure testing of said device within said pressure
vessel.
18. A clamping device for an elongated element comprising a clamping
enclosure disposed about at least a part of said element, freeze means
between said part of said elongated element and said enclosure, said
freeze means including a frozen material exerting a force inwardly against
said part of said element and outwardly against said enclosure by virtue
of having been frozen in situ such that said frozen material thereby
clamps said elongated element to said enclosure, and pulling means
attached to said enclosure for pulling said enclosure such that pulling of
said enclosure effects pulling of said elongated element.
19. A freeze device according to claim 18 wherein said conductor is a
cable.
20. A method for clamping an elongated element comprising disposing a part
of said elongated element in a clamping enclosure, introducing a freezable
material into said enclosure, surrounding said part of said elongated
element with said freezable material, freezing said freezable material in
situ in said enclosure such that the frozen material exerts an inward
force against said part of said elongated element and an outward force
against said enclosure, clamping said part of said elongated element to
said enclosure by said forces exerted by said frozen material and
effecting tensioning between said enclosure and aid elongated element
while said part of said elongated element is clamped to said enclosure.
21. A method according to claim 20 wherein said frozen material is ice.
22. A method according to claim 20 wherein said step of freezing said
freezable material comprises utilizing carbon dioxide to effect said
freezing.
23. A method according to claim 20 wherein said step of freezing said
freezable material comprises utilizing dry ice to effect said freezing.
24. A method according to claim 20 wherein said step of freezing said
freezable material comprises utilizing a cryogenic material to effect said
freezing.
25. A method according to claim 20 wherein said elongated element is an
underwater conductor which is adapted to be disposed under water during
normal use, said conductor being placed under water by a ship, said
conductor having a portion which is temporarily disposed on said ship as
another portion of the conductor is being placed under water, further
comprising utilizing the clamping of said part of said conductor to said
enclosure on said ship for effecting clamping of said portion of said
conductor which is temporarily disposed on said ship.
26. A method for sealing an elongated element comprising providing a
pressure vessel having an interior and first through passage leading to
said interior, disposing a first part of said elongated element in said
through passage and a second part in said interior of said pressure
vessel, introducing a freezable material into said through passage,
surrounding said first part of said elongated element with said freezable
material, freezing said freezable material in situ in said through passage
such that the frozen material exerts an inward force against said first
part of said elongated element and an outward force against said through
passage, and sealing said first part of said elongated element in said
through passage of said pressure vessel by said force exerted by said
frozen material.
27. A method according to claim 26 further comprising pressurizing said
interior of said pressure vessel, and pressure testing said elongated
element in said pressurized pressure vessel.
28. A method according to claim 26 wherein said elongated element is a
conductor, further comprising connecting a to-be-tested device to said
second part of said conductor, disposing said device in said interior of
said pressure vessel, and pressure testing said device in said pressurized
pressure vessel as said frozen material effects sealing of said pressure
vessel.
29. A method according to claim 26 wherein said through passage is
designated first through passage, further comprising providing a second
through passage Leading to said interior of said pressure vessel,
disposing a third part of said elongated element in said second through
passage on said pressure vessel with said second through passage being
spaced from said first through passage, said second part of said elongated
element being disposed between said first and third parts of said
elongated element, introducing said freezable material into said second
through passage of said pressure vessel, surrounding said third part of
said elongated element with said freezable material, freezing said
freezable material in situ in said second through passage such that said
frozen material in said second through passage exerts an inward force
against said third part of said elongated element and an outward force
against said second through passage of said pressure vessel respectively,
sealing said pressure vessel utilizing said frozen material in said second
through passage of said pressure vessel, pressurizing said sealed
pressurized vessel to thereby pressure test said second part of said
elongated element in said pressure vessel.
30. A method according to claim 29 whereby said second part of said
elongated element has a to-be-tested device connection thereto, further
comprising disposing said device in said pressure vessel, said step of
pressurizing said sealed pressurized vessel comprising pressure testing
said device in said pressurized pressure vessel.
31. A method according to claim 26 wherein said through passage is
designated a first through passage, further comprising providing a second
through passage leading to said interior of said pressure vessel,
disposing a third part of said elongated element in said second through
passage of said pressure vessel with said second through passage being
spaced from said first through passage, said interior of said pressure
vessel extending between said first and second through passages, said
second part of said elongated element being disposed in said interior of
said pressure vessel, introducing said freezable material into said second
through passage and into said interior of said pressure vessel,
surrounding said second part and said third part of said elongated element
with said freezable material, freezing said freezable material in situ in
said second through passage such that the frozen material in said second
through passage exerts an inward force against said third part of said
elongated element and an outward force against said second through passage
of said pressure vessel respectively, and trapping said freezable material
in said interior of said pressure vessel by the frozen material in said
first and second through passages of said pressure vessel.
32. A method according to claim 31 further comprising controlling the
amount of trapped freezable material in said interior of said pressure
vessel to enhance the clamping effect of the freezable material on said
elongated element.
33. A method according to claim 31 further comprising continuing to effect
freezing of said freezable material in said first and second through
passages such that said continued freezing moves longitudinally in said
pressure vessel toward said interior of said pressure vessel, whereby said
continued freezing enhances the clamping effect of the freezable material
on said elongated element.
34. A method for clamping an elongated element comprising disposing a part
of said elongated element in a clamping enclosure, introducing a freezable
material into said enclosure, surrounding said part of said elongated
element with said freezable material, freezing said freezable material in
situ in said enclosure such that the frozen material exerts an inward
force against said part of said elongated element and an outward force
against said enclosure, clamping said part of said elongated element to
said enclosure by said forces exerted by said frozen material, and
utilizing a pulling mechanism attached to said enclosure for pulling said
enclosure which in turn pulls siad elongated element.
35. A method according to claim 34 wherein said elongated element is an
underwater conductor which is adapted to be disposed under water during
normal use, further comprising utilizing said clamping of said part of
said elongated element to said enclosure on a ship for effecting clamping
of said underwater conductor.
36. A clamping device for clamping an elongated element to a clamping
enclosure disposed about a part of said element, freeze means between said
part of said elongated element and said enclosure, said freeze means
including a frozen material exerting a force inwardly against said part of
said element and outwardly against said enclosure by virtue of having been
frozen in situ such that said frozen material thereby clamps said
elongated element to said enclosure, and tensioning means for effecting
tensioning between said clamping enclosure and said elongated element such
that said tensioning means tensions said elongated element as said part of
said elongated element is clamped to said clamping enclosure.
Description
BACKGROUND OF THE INVENTION
This invention relates to a freeze seal and freeze clamp for cables, wires,
optical fibers and other elements requiring a seal or a clamp.
The present invention can be used, for example, for testing cables or
hardware components having a cable connected thereto. Undersea cable and
undersea hardware components for example require testing during
development and as part of quality assurance. According to one procedure,
in order to test such cable or hardware component, the cable or hardware
component is disposed in a pressure vessel and the pressure vessel
pressurized to the desired test pressure. However, it is necessary that
the cable extend externally of the pressure vessel because only a small
section or mid-span portion of an elongated cable may be tested or because
the hardware component being tested has a cable connected thereto which
extends externally of the pressure vessel. Since the cable is required to
penetrate the pressure vessel, it is necessary to provide a seal between
the cable and the pressure vessel in order that the pressure vessel can be
pressurized.
Heretofore, such seal was a gland seal which was specifically modified to
accommodate the requirements of the particular cable which penetrated the
pressure vessel. For example, the seal would have to be modified depending
on the physical characteristics of the particular cable being tested such
as its diameter, cross sectional geometry, surface characteristics, the
material of the cable and whether there was one or more cables to be
sealed. Such modifications would often result in requiring a redesign of
the seal for different cables in order to adapt the seal to the particular
cable or cables to be tested.
It is desirable that a seal used for testing of such cables and hardware
components include the following characteristics:
(a) the seal should be a universal pressure seal that conforms directly to
the outer layer of the cable regardless of cable size, construction, or
surface condition;
(b) the seal should have a zero leak rate;
(c) the seal should provide a force capable of restraining the cable from
moving through the seal at the maximum chamber pressure;
(d) the seal should be easy to install and remove;
(e) the seal should not damage or degrade the performance of the cable; and
(f) the seal should operate on cables at the free ends or at mid-span, that
is, the pressure vessel and cable seal can be modified to a split design
that is capable of capturing the cable anywhere along the length of the
cable, for example, for local pressure testing of a repeater or splice
housing in the center or mid-span of a long cable on a factory floor.
SUMMARY OF THE INVENTION
The present invention is able to satisfy all of these criteria while at the
same time effecting a seal on various cables having a wide variety of
physical characteristics without requiring redesign or major modification
of the seal. The present invention is also able to effect a clamping
action on the cable to securely clamp the cable to the pressure vessel.
The present invention is also able to provide a seal for small diameter
elements such as optical fibers. For example, one or more optical fibers
may be connected to a hardware component requiring pressure testing in a
vessel subjected to pressure. The present invention can provide a freeze
seal for the optical fiber to enable the optical fiber to extend
externally of the pressure vessel to enable pressure testing of the
hardware component within the pressurized testing vessel.
The present invention is also directed to a freeze clamp wherein the freeze
clamp provides a clamping force which clamps a cable or other element to
be clamped and enables application of a tension force to pull or lift the
cable or other element in various applications such as manipulating an
undersea cable.
Accordingly, it is an object of the present invention to provide a freeze
seal and a freeze clamp which overcomes the disadvantages of the prior
art.
It is another object of the present invention to provide a freeze seal and
freeze clamp which is easy to install and remove.
It is still another object of the present invention to provide a freeze
seal and freeze clamp which is a reliable pressure seal and clamp
regardless of cable construction, diameter, geometry or surface condition.
It is yet another object of the present invention to provide a freeze seal
and freeze clamp which is a universal seal that conforms directly to the
outer layer of the cable regardless of cable size, construction, or
surface condition.
It is a still further object of the present invention to provide a freeze
seal and freeze clamp that provides a force capable of restraining the
cable from sliding through the seal.
It is another object of the present invention to provide a freeze seal and
freeze clamp which does not damage or degrade the performance of the
cable.
It is still another object of the present invention to provide a freeze
seal and freeze clamp which will operate on cables at the free ends or in
mid-span, that is, the pressure freeze seal and freeze clamp can be
modified to a split design that is capable of capturing the cable anywhere
along the length of the cable, for example, for local pressure testing of
a repeater or splice housing in the center or mid-span of a long cable on
a factory floor.
In accordance with one aspect of the present invention, a freeze seal for
testing and qualifying cables and components connected to the cable
includes a pressure vessel having the cable and the component to be
pressure tested disposed in the pressure vessel with at least one part of
the cable extending out of one or both ends of the pressure vessel. A
freeze jacket surrounds one or both ends of the pressure vessel and
defines an annular freeze seal area about one or both ends of the pressure
vessel. A liquid supply means is connected to the pressure vessel for
supplying a liquid under pressure such that the liquid flows into the
pressure vessel surrounding the cable and the component to be tested. A
freezing means is connected with the freeze jacket for supplying a
freezing material to the annular freeze seal area, the freezing material
having a temperature sufficient to freeze the liquid in the annular freeze
seal area such that the frozen liquid forms a pressure freeze seal at one
or both ends of the pressure vessel.
The freezing means can include a fluid that is conducted into the annular
freeze seal area. In another method, dry ice may be placed in the annular
freeze seal area.
In accordance with another aspect of the present invention, a freeze seal
for testing of equipment and cables, includes a pressure vessel having the
equipment to be tested and the cables therein, with at least one cable
section extending out of the end of the pressure vessel. An extension tube
is mounted adjacent to at least one end of the pressure vessel and is in
open communication with the pressure vessel, with the at least one cable
section extending from the pressure vessel out of the extension tube. A
freeze jacket surrounds the extension tube and is spaced from the
respective extension tube so as to define an annular freeze seal area
therebetween. Liquid supply means is connected with the pressure vessel
for supplying a liquid under pressure such that the liquid passes to an
annular freeze seal area in the extension tube surrounding the cable.
Freezing means is connected with the freeze jacket for supplying a
freezing material to the annular freeze seal area, the freezing material
having a temperature sufficient to freeze the liquid in the annular freeze
area such that the frozen material forms a pressure freeze seal.
The freezing material may be of any type which is capable of providing the
desired freezing and may include, for example, carbon dioxide, dry ice, or
a cyrogenic fluid. The liquid supply means includes a delivery system for
supplying the liquid into the freeze jacket under pressure.
The present invention is also directed to a freeze clamp wherein the freeze
clamp provides a clamping force which clamps a cable or other element to
be clamped and enables application of a tension force to pull or lift the
cable or other element in various applications such as manipulating an
undersea cable.
The above and other objects, features and advantages of the invention will
become readily apparent from the following detailed description thereof
which is to be read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view, partly broken away, showing a freeze seal
according to one embodiment of the invention.
FIG. 2 is a sectional view taken along the line 2--2 in FIG. 1.
FIG. 3 is a sectional view taken in a manner similar to that of FIG. 2 but
showing an alternative embodiment in which the pressure vessel which is
formed in two halves with the two halves being fastened by fastening
means.
FIG. 4 is an elevational view of another embodiment of the invention
wherein the freeze seal is mounted on a pressure vessel.
FIG. 5 is a schematic and perspective view showing two freeze seals mounted
on a pressure vessel.
FIG. 6 shows an alternate embodiment wherein a plurality of different size
conductors are sealed within the freeze seal.
FIG. 7 is a view showing a test arrangement for evaluating the freeze seal
when used with optical fibers.
FIG. 8 is a view similar to FIG. 7 but wherein the optical fibers in the
freeze seal are disposed in tubes.
FIG. 9 is a perspective view of a portion of FIG. 8.
FIG. 10 is a graphical diagram of the results of optical loss versus time
for the pressure test used in FIG. 7.
FIG. 11 is a graphical diagram of additional results of optical loss versus
time for the pressure test used in FIG. 7.
FIG. 12 is a graphical diagram of the results of optical loss versus time
for the pressure test used in FIGS. 8 and 9.
FIG. 13 is a graphical diagram of additional results of optical loss versus
time for the pressure test used in FIGS. 8 and 9.
FIG. 14 is a graphical diagram of the results of optical loss versus time
for a modified pressure test used in FIGS. 8 and 9.
FIG. 15 is a graphical diagram of additional results of optical loss versus
time for the modified pressure test used in FIGS. 8 and 9.
FIG. 16A is a cross sectional view of another embodiment showing a freeze
seal used to seal an optical fiber.
FIG 16B is a partial cross sectional view of another embodiment in which
the freeze seal shown in FIG. 16A is used with pressure vessel in FIG. 4.
FIG. 17 is a sectional view taken along the lines 17--17 in FIG. 16.
FIG. 18 is an elevational view showing a freeze seal used as a clamp.
FIG. 19 is a perspective view showing a freeze seal used as a clamp.
FIG. 20 is a schematic view showing a freeze seal and freeze clamp used on
a ship for handling undersea cable.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings in detail, and initially to FIGS. 1 and 2
thereof, a portable pressure vessel facility includes a pressure vessel 12
in the form of a pipe or tube and preferably made of steel. Pressure
vessel 12 includes an inner chamber 14 for containing a hardware component
15 which is connected to cable 16. The cable 16 extends within chamber 14
and exits at opposite ends of pressure vessel 12. By way of example, the
pressure vessel 12 may have a length of ten feet while opposite ends of
the cable 16 extending out of pressure vessel 12 are wound on respective
reels (not shown).
A conduit connection 18 is connected to pressure vessel 12 and is in
communication with chamber 14. A pump 20 is connected to conduit 18 to
supply water or other liquid under pressure to chamber 14. A valve 22 is
preferably connected with the conduit to control the flow of liquid
therethrough and/or to control the pressure of liquid.
Two pressure vessel cable seals 23 are mounted at opposite ends of pressure
vessel 12 in surrounding relation thereto. Each cable seal 23 includes a
freeze jacket 24 which is disposed about the outer periphery of the
pressure vessel 12. The freeze jacket 24 is made of one or more layers of
a fabric material and insulating material and is wrapped around the
pressure vessel and secured in place by fastening means (not shown) such
as Velcro in a manner resembling application of a blood pressure cuff to a
person's arm when taking a blood pressure reading. The longitudinal ends
of the freeze jacket 24 are tightly secured to the pressure vessel by
fastening means such as by tape 27. Alternatively, other securing means
such as string or rope may be used. A conduit 29 is provided through the
freeze jacket 24 to allow a freeze material to pass into the annular space
31 between the freeze jacket 24 and the outside of the pressure vessel 12
as will be further described. A pressurized container 26 of a freezing
material, such as liquid carbon dioxide, is connected to each freeze
jacket 24 through a suitable conduit 28 to supply liquid carbon dioxide to
the annular space 31 between the inner surface of freeze jacket 24 and the
outer wall of pressure vessel 12. As pressurized liquid of carbon dioxide
is throttled into the annular space 31 between the freeze jacket 24 and
the pressure vessel 12 and a portion of it flashes to gas while the
remainder solidifies into dry ice in the annular space 31.
The advantages of using a fluid such as carbon dioxide are that it does not
require special venting to the atmosphere, it can be used outside of
pressure vessel 12, there is low local power required and there is a
mechanical simplicity due to its self-pressurizing characteristics.
Of course, freezing means other than liquid carbon dioxide can be used. For
example, a refrigerant system using a compressor, heat exchanger and
condensate pump can be used. Alternatively, a cryogenic liquid can be
pumped to the freeze jackets 24, thereby using a liquid/gas phase change
to absorb the heat of vaporization. Still further, a thermoelectric
cooling system can be used. In addition, dry ice may be manually placed
between the freeze jacket 24 and the pressure vessel 12 with the dry ice
being retained in place by the freeze jacket 24.
In basic operation, the hardware component 15 and associated cable 16 to
which hardware component 15 is connected is placed in pressure vessel 12.
A temporary water-block is installed in the annular space 33 between the
cable 16 and the pressure vessel 12 at the longitudinal end of the
pressure vessel 12. The temporary water block may be clay, rubber or other
similar material which may be formed into different shapes at ambient
temperature. Chamber 14 of pressure vessel 12 is then filled with water
(not under pressure). Carbon dioxide from supply tank 26 is throttled into
the freeze jackets 24, thereby forming dry ice in the annular space 31 by
using the heat of vaporization. The water in the annular space 33 within
that portion of pressure vessel 12 surrounded by cable seals 23 and in
surrounding relation to cable 16, freezes into ice, thereby creating ice
33a and resulting in freeze seals thereat.
Pressure vessel 12 is then pressurized by pump 20. Because of the freeze
seals that are formed, liquid no longer can escape from chamber 14.
Specifically, the ice 33a in annular chamber 33 exerts a radial inner
compressive force on cable 16 and an outer radial force on pressure vessel
12 during the final stage of ice formation. This is due to the expansion
of the ice 33a during freezing. The adhesion of the ice 33a to the walls
of pressure vessel 12 and to cable 16 contributes to the sealing. Further,
forces generated by the ice 33a can be controlled by controlling the ice
formation.
At the conclusion of the testing, the pressure is released inside pressure
vessel 12, and freeze jackets 24 are removed. After the ice 33a melts, the
water is drained and the hardware component 15 and cable 16 are removed
from pressure vessel 12. The freeze jacket 24 may be heated if quick
removal of the ice seal is desired.
FIGS. 3 shows a further embodiment wherein a metal pressure vessel 12a is
made up of two halves 12b and 12c which are joined together by fastening
means such as nuts and bolts 12d. A resilient gasket 34 is disposed
between the two halves 12b, 12c. A cable 16a extends through the pressure
vessel 12a. FIG. 3 further shows the freeze jacket 24a, the freeze
material in annular space 31a, and the ice 33a in annular space 33. These
parts are Similar to the corresponding parts in the embodiment of FIGS. 1
and 2 with letter subscripts have been added to the numerals to identify
the corresponding similar parts. With this construction the two halves
12b, 12c can be separated in order to receive an intermediate part or
mid-span part of an elongated cable 16a which may be coiled on coils.
The freeze seal according to the present invention will operate with
different configurations and in different environments. For example, in
the arrangement of FIGS. 1 and 2, the freeze seals 23 are disposed in
surrounding relation to pressure vessel 12. However, in another embodiment
as shown in FIG. 4, freeze seal 40 is disposed at an end wall 42 of a
pressure vessel 44. The freeze seal 40 includes a freeze seal structure 46
mounted on pressure vessel 44 by mounting means such as the threads 48 on
the seal structure 46 engaging the mating threads on the pressure vessel
44, a seal 50 of resilient material being provided between the seal
structure 46 and the pressure vessel 44. The seal structure 46 is made of
metal and has a freeze chamber 52 having an inner wall 52a spaced from an
outer wall 52b and end walls. A conduit 54 supplies freeze material to the
freeze chamber 52 while conduit 55 is a vent or a return.
An annular freeze space 56 between the inner wall 52a and a cable 16c is in
open communication with inner chamber 44a of pressure vessel 44 via
passage 43 so as to fill with liquid, e.g. water, that is pumped into
inner chamber 44a. A seal such as a split rubber cone 58 is positioned
over cable 16c at the free end of seal structure 46 and functions as a
liquid seal, as insulation and to center cable 16c. A foam insulation 60
surrounds the seal structure 46 to further insulate the freeze seal.
In operation, a hardware component 62 and an associated cable or cables 16c
that are to be tested are placed in the pressure vessel 44 with the cable
16c extending through the seal structure 46. Pressure vessel 44 is then
filled with water (not under pressure) via a conduit (not shown), and a
cryogenic liquid is introduced into seal chamber 52 via conduit 54. The
liquid in annular freeze space 56 freezes into ice 56a, thereby creating
an ice seal in the annular freeze space 56. The pressure vessel 44 is then
pressurized. Because of the ice 56a that is formed between the cable 16c
and the seal structure 46 no liquid escapes from chamber 44. At the
conclusion of the testing, the pressure is removed from pressure vessel 44
and after the ice 56a melts, the water is drained and the hardware
component 62 and cable 16c are removed from the pressure vessel 44.
FIG. 5 is a schematic view showing another embodiment wherein a hardware
component 63 connected to a cable 16d is tested in a pressure vessel 44a.
Two freeze seals 40a and 40b, such as the freeze seal 40 shown in FIG. 4,
are mounted on the end wall 42a of the pressure vessel 44a to thereby
simultaneously seal two mid-span portions of the cable 16d. The pressure
vessel 44a is pressurized to test the component 63 as the freeze seals
40a, 40b seal the cable 16d which passes outside of the pressure vessel
44a.
Any number of cables of various diameter, cross sectional configuration,
geometric shape and material composition may be freeze sealed according to
the present invention. For example the embodiment of FIG. 6 shows a freeze
seal 65 which simultaneously freeze seals a plurality of cables of various
diameters as indicated at 16e through 16j.
Returning now to the embodiment of FIGS. 1 and 2, an undersea cable
pressure test was performed using this embodiment. In this test, the
sample cable 16 was placed in pressure vessel 12 which was then filled
with water. Thermocouples placed on the cable 16 were used to measure the
temperature and length of the ice seal. Carbon dioxide was injected into
freeze jacket 24, thereby creating dry ice (-110.degree. F.). The dry ice
in contact with the exterior of the pressure vessel 12 created an ice seal
33a eight inches long in about 15 minutes. After the ice seal was
established, the pressure was increased in 1000 psi increments up to a
minimum of 5000 psi (maximum of 6200 psi). After a dwell time of 5
minutes, the pressure was reduced to 4,000 psi and the jacket 24 and dry
ice were removed. The ice or freeze seal was then allowed to fail under
pressure. The time and temperature of the ice at failure was recorded. To
test for plastic deformation, the outside diameter along the length of
pressure vessel 12 was recorded in six inch increments before and after
each test.
The tests included the following samples:
a) No cable was used.
b) A fifteen foot length of AT&T SL Deep Water undersea cable was tested in
a 1.5 inch and 2.5 inch pressure vessel 12. The cable had an outside
diameter of 0.8 inch with an outer jacket of polyethylene. The diameter of
the cable was measured along the length before and after each test, in
order to determine if the freeze seal caused permanent deformation to the
cable.
c) A fifteen foot length of AT&T SL single-armor undersea cable was tested
in the 2.5 inch diameter pipe. The cable had an outside diameter of 1.5
inches, with an outer layer of tar and jute. In one test, the cable was
used, as is, and in another test, one end of the cable was prepared by
removing the tar and jute, exposing the armor-wires. The bedding under the
armor-wires was then removed. This test was conducted in order to
determine if a grossly damaged cable could be sealed using the freeze
seal.
d) An optic fiber was used.
The results of the pressure tests are represented by the following table 1:
TABLE 1
__________________________________________________________________________
Time to Failure
Pipe ID Max. Pressure
(after jacket
(inches)
Cable Type
(psi) removal)
Temperature
Observation
__________________________________________________________________________
1.5 no cable
6200 21 minutes no yielding
1.5 SL Deep Wtr
6200 130 minutes
-18.degree. F.
no damage
(jacket was
not removed)
2.5 no cable
6200 35 minutes no yielding
2.5 SL Deep Wtr
6200 43 minutes
-24.degree. F.
no damage
2.5 SL Single Arm.
6200 30 minutes
-20.degree. F.
no damage
2.5 SL Single Arm.
6200 30 minutes
-20.degree. F.
no damage
Jute & bedding
removed
1.5 Optic Fiber
5000 Did not test to failure
no damage
2.5 Optic Fiber
5000 Did not test to failure
no damage
__________________________________________________________________________
The undersea cable pressure test results indicate that the SL Deep Water
(0.8 inch diameter, polyethylene jacket) cable, was successfully tested to
6200 psi using the freeze seal in both the 1.5 inch and 2.5 inch pressure
vessel 12. There was no appreciable change in the outside diameter of
cable 16 after any of the tests. This is an indication that the
compressive or clamping force of the ice does not damage the cable. The
outside diameter of pressure vessel 12, in the area of the freeze seal,
did not increase after the testing, indicating that the expansion of the
ice did not cause permanent yielding of the walls of pressure vessel 12.
The outside diameter along the length of pressure vessel 12 did not
increase, indicating that repeated internal hydraulic pressures of 6,200
psi did not cause permanent yielding.
The SL single armor (1.5 inch diameter, tar and jute coated) cable was
successfully tested to 6,200 psi in the 2.5 inch pipe. After the seal was
established, the pressure was gradually increased to 1,000 psi. It was
noticed that the pressure dropped slightly over several minutes. After the
initial pressure drop, the pressure was increased back to the 1,000 psi
without any further loss in pressure. After each 1000 psi increase up to
the maximum 6,200 psi the same sequence of events was observed. The
pressure loss that was present in the single-armor cable may be due to the
way in which the cable was tested. The dry cable was placed in pressure
vessel 12 and the ice or freeze seal established within ten minutes. Water
may not have been able to penetrate under the tar and Jute coating within
the ten minute seal installation period. Water could have been forced into
the dry voids under the tar and Jute jacket during the pressurization,
causing the pressure drop. When the liquid water comes into contact with
the -30.degree. F. freeze seal boundary the water is frozen, thereby
reestablishing the pressure seal. This type of action can be thought of as
a "self healing" attribute of the freeze seal.
In addition to the above testing, a further fiber optical pressure test was
performed on optical fibers which have a very small diameter, for example,
in the order of 0.01 inches average diameter. In this test, as shown in
FIG. 7, two optical fibers 16k were placed in pressure vessel housing 12k.
Optical losses for both fibers 12k were recorded continuously during ice
formation, vessel pressurization, de-pressurization and ice removal. Three
pressure tests were conducted to a maximum pressure of 5,000 psi.
The first optical fiber pressure test used a Dow Corning 100/140 Multimode
fiber and an AT&T Depressed Clad single mode fiber installed in the
pressure vessel shown in FIG. 7. As shown therein, the first optical fiber
pressure test was run by simply looping optical fibers 16k in a pressure
vessel housing 12k and forming freeze seals 33k at opposite ends thereof
by means of freeze jackets 27k. Optical fibers 16k extending from pressure
vessel 12k were connected at one end to a laser 67 which transmitted light
through the optical fibers 16k and at their opposite ends to an optical
power meter 69 which measured the light output therefrom. Water 71 under
pressure was pumped into pressure vessel 12k between the ice seals 33k.
The results of this first test, as shown in FIGS. 10 and 11, indicate that
the optical loss steadily increases over time, starting to increase during
the ice formation and continuing until the end of the pressure test.
Optical measurements were taken before the ice seals were installed,
during ice seal installation, and during pressurization. The optical loss
returned to the pretest values after 24 hours. It was concluded that the
fibers 16k could not be placed into the freeze seal unprotected because of
unacceptable optical loss.
As a result of poor optical performance found in the first test, a second
optical fiber pressure test was performed, as shown in FIGS. 8 and 9,
using the same Dow Corning and AT&T fibers inserted into 1/8 inch internal
diameter stainless tubes 66.
In this second test, four tubes 66 were used, having optical fibers 16 m
running through the centers thereof, with the four tubes 66 being attached
to a 1/4" thick.times.1" wide.times.15" long metal strip 75 by fastening
means such as a common wire tie (not shown). Three temperature sensors 77,
79 and 81 were mounted to metal strip 75 to supply signals corresponding
thereto via connecting conductors 83 to a temperature monitor 90 which
monitored the ice temperature.
The results of the second optical test indicated that there was little
optical loss during the first 10 minutes of the test, as shown in FIGS. 12
and 13. After 10 minutes, there was an abrupt increase in optical loss. A
careful review of the temperature monitoring equipment indicated that at
10 minutes into the test, ice formed around one end of the protective
tubes 66. Interaction of the ice at the end of the tube/fiber interface
could have resulted in increased optical loss. Again, optical measurements
were taken before the ice seals were installed, during ice seal
installation, and during pressurization.
Improvements in the optical performance of the second test resulted in
changes in the test set-up for a third optical fiber pressure test.
Specifically, the fibers were inserted into 0.032" internal diameter brass
tubes (not shown). The brass tubes were then inserted into the 1/8 inch ID
stainless steel tubes 66 and installed into the test setup shown in FIGS.
8 and 9. The protective tubes 66 were carefully positioned in the freeze
seal, to ensure that ice would not form around the ends of tubes 66. Test
results show extremely low optical loss during ice generation and during
the pressure test, as shown in FIGS. 14 and 15. Again, optical
measurements were taken before the ice seals were installed, during ice
seal installation, and during pressurization.
FIGS. 16A and 17 show a further embodiment wherein an optical fiber 16p is
connected to a component 15p to be pressure tested using test equipment
17p. The component 15p is disposed in a pressure vessel 12p and the
optical fiber 16p extends out of both ends of the pressure vessel 12p.
Freeze jackets 24p on the outside of each end portion of the pressure
vessel 12p provide a freeze seal at both ends of the pressure vessel 12p.
The optical fiber 16p extends through an inner tube 65p (shown in FIG. 17
only) which in turn extends through an outer tube 66p. The tubes 65p, 66p
are sufficiently long to extend longitudinally beyond the longitudinal
ends of the ice 33p which forms the seal to ensure that ice does not form
around the ends of the tubes 65p, 66p. After the freeze seals are
established, the vessel 12p is pressure tested with fluid supplied via
conduit 18p to perform the pressure testing.
Instead of the optical fiber 16p extending out of both ends of the pressure
vessel 12p, it may extend out of only one end. Also only one optical fiber
16p may be connected to the component 15p instead of the two shown in FIG.
16A.
FIG. 16B shows another embodiment in which the freeze seal of 16A is used
with a pressure vessel 44z, such as shown in FIG. 4, in which a hardware
component 62z is pressured tested. The freeze seal of FIG. 16B included a
freeze jacket 24z, inner tube 65z and an elongated element 75z. The inner
tube 65z is not shown in FIG. 16B but would be the same as inner tube 65p
shown in FIG. 17.
The optical fibers may comprise glass either coated or uncoated. An example
of the diameter of the optical fiber is in the order of 0.01 average
diameter.
A tension test was performed to determine the cable clamping force
generated by the freeze or ice seal. If the freeze seal can generate
enough clamping force to prevent the cable from being forced out of
pressure vessel housing while under pressure, the freeze seal can act as a
combination seal and clamp.
Careful observations of the ice formation revealed that the ice is formed
in thin layers starting from the pipe wall in the region under freeze
jacket. As the thin layers freeze, expansion of the ice displaces water at
the water/ice boundary. The final layer to freeze traps a small amount of
water next to the cable/ice boundary. Expansion of this water during the
freezing process produces a cable clamping force. By controlling the
amount of "trapped" water next to cable it may be possible to adjust the
clamping force generated by the ice. Adhesion of the ice to the cable wall
also add to the shear resistance.
The first tension test determined the clamping force generated by the
freeze seal during a "normal" freeze process. The second "modified"
tension test increased the clamping force of the seal by altering the ice
formation process within the seal. Specifically, the longitudinal ends of
the seal were first frozen, trapping water in the central longitudinal
portion of the seal such that when the trapped water in the central
longitudinal portion subsequently started to freeze, an increased clamping
force resulted because there was no space for the freezing water in the
trapped central longitudinal portion to expand.
The sample cables were installed in the test setup shown in FIG. 18.
Specifically, one end of cable 16x was fixed to a support 80 by a clamp
82, while the opposite end of cable 16x extended through the pressure
vessel 12x which was surrounded by a freeze jacket 24x, as in FIG. 1. A
frame 84 having a crosshead 85 abutted against the upper end of pressure
vessel 12x had a pulling force applied thereon by pulling means 86
connected thereto. The force that was applied was in a direction away from
support 80. As in the embodiment of FIG. 1, an ice or freeze seal was
formed between pressure vessel 12x and cable 16x, the length D of the
freeze seal being approximately 8.0 inches.
Each sample was pull tested to failure or a maximum of 15,000 pounds. The
results of the tests are shown in the following Table 2. Careful
observation of the outer jacket of cable 16x was made before and after
each pull test to determine if damage occurred during the test.
TABLE 2
______________________________________
Pipe ID Max Tension
Freeze Obser-
(inches)
Cable Type (psi) method vation
______________________________________
1.5 SL Deep Water
1250 Normal no damage
0.8" Dia.
Poly Jacket
1.5 SL Deep Water
5010 Modified
no damage
2.5 SL Deep Water
1200 Normal no damage
2.5 SL Deep Water
5500 Modified
no damage
2.5 SL Single 15000 Normal no damage
Armored
Jute Jacket
1.5" Dia.
______________________________________
The results of the tension test reveal that the freeze seal can act as the
sole cable restraint during most applications of high pressure testing.
Thus, testing of the freeze seal has demonstrated that it is a universal,
easy to install, high pressure seal that is unaffected by cable
construction, diameter or surface condition. The freeze seal has a simple
robust design that can be incorporated into existing pressure vessel
systems.
Further, "off the shelf" pipes can be used as the pressure vessel housing
for high pressure testing of cable systems and undersea components.
FIG. 19 shows a freeze seal 23y used as a clamp for clamping an elongated
element 16y which may be a nonelectrical component such as a rope, rod or
other structural member. The elongated element 16y may be used for various
purposes for example for supporting a weight W or for providing tension or
compression on a structure.
FIG. 20 shows a freeze seal and/or a freeze clamp 23z used on a ship S. The
freeze clamp 23z can be used on the ship as a clamp for clamping an
undersea cable 16z as it is raised from and/or lowered to the ocean floor.
Also the freeze seal 23z can be used on the ship as a seal for pressure
testing the cable 16z, pressure testing splices on the cable 16z and
pressure testing components connected to the cable 16z.
Although water is mentioned as the pressurizing fluid for the pressure
vessel 12, other fluids may also be used.
The freeze seal may also be incorporated into a temporary cable tensioning
device that can replace the spelter socket (requires potting of the armor
wires at the end of the cables) and Kelly Grips ("Chinese finger" device
woven around the cable) in some applications.
Having described specific preferred embodiments of the invention with
reference to the accompanying drawings, it will be appreciated that the
present invention is not limited to those precise embodiments and that
various changes and modifications can be effected therein by one of
ordinary skill in the art without departing from the scope or spirit of
the invention as defined by the appended claims.
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